This invention relates to tufting machines and more particularly to a cut/loop hook and the mounting of a clip thereon.
In a tufting machine a multiplicity of yarn carrying needles penetrate a backing material to insert loops of yarn therein which loops are seized and shed by a looper to produce loop pile or are seized and maintained by a hook and thereafter cut by a knife to produce cut pile. To produce loop and cut tufts in the same row of stitching it is now notoriously well known to use a spring clip secured to a cut pile hook and biased against the bill of the hook. This basic procedure is illustrated in Card U.S. Pat. No. 3,084,645 in which the amount of yarn fed to the needles is controlled so that on selective stitches less yarn is fed to a selective needle to backdraw yarn from a previous loop to cause that loop to force the spring clip away from the bill of the hook and be withdrawn from the hook to form an uncut loop. When sufficient yarn is fed to the needle no yarn is backdrawn from the previous loop and the loop remains on the hook and is later cut by a knife.
As the gauge of the tufted products have gradually decreased, i.e., the spacing between adjacent rows of stitches and thus between respective needles, loopers or hooks, various looper and hook mounting constructions have been developed. For example, modules have been developed wherein the shanks of respective loopers or hooks are embedded in a common body member in side-by-side disposition. Such constructions are illustrated in Bardsley U.S. Pat. No. 4,303,024 and Biggs et al U.S. Pat. No. 4,313,388. Such construction substantially eliminates the difficulties of aligning hooks or loopers in a respective hook or looper bar of the tufting machine since the hooks or loopers are aligned in a jig during the formation of the module. Moreover, to produce cut/loop a module has been developed as illustrated in Bardsley U.S. Pat. No. 4,241,675 in which the hooks are mounted in a first body member and the clips are mounted in a second body member and the body members are adapted and arranged to locate the hooks and clips in the requisite cooperative relationship.
One difficulty with the modular construction is that of replaceability of a broken gauge part, i.e., a hook, looper or clip. If a gauge part breaks then the entire module must be removed and replaced, the module including the unbroken gauge parts generally being discarded or returned for remanufacture. For fine gauge machines, such as 1/16 of an inch and smaller, this problem is justified by the advantages of precise alignment of the gauge parts and reduced deflection. For coarser gauges in the order of 1/8 to 1/10 inch, however, from a cost effectiveness standpoint rapid replaceability of a broken gauge part may be more significant than the advantages of a module. For this reason gauge part mounting blocks have been developed which permit the body and shank of the loopers or hooks to be supported over a large area, have accurate reference positioning surfaces, have means for securing the loopers or hooks in the block firmly, and yet permit individual gauge parts to be replaced. Such a construction is illustrated in Ingram copending U.S. patent application Ser. No. 524,150, filed Aug. 18, 1983, and assigned to the common assignee of the present invention. However, no effective means for providing cut/loop has been developed for such gauge part mountings. Thus, although it may be desirable to use a clip mounting as disclosed in the aforesaid Bardsley U.S. Pat. No. 4,241,675, nevertheless, with that construction when one clip is broken an entire module of clips must be replaced.
There have been attempts in the past to mount the spring clip of a cut/loop hook on the hook shank in such a manner that the clip does not protrude beyond the face of the hook shank. In Japan one manufacturer has attempted to produce such a construction which utilized a hook having a slot in the shank for receiving the shank of a spring clip, the clip being conventionally riveted or spot welded to the shank of the hook. With such a construction, however, if a clip is broken the entire hook and clip must be removed from the mounting block and replaced by another similar combination hook and clip. Such construction becomes impracticable with the gauge part mounting blocks of the aforesaid Ingram patent application, and since a clip is a relatively small cost component of the total cost of a cut/loop hook-clip combination, the need to discard such a combination on account of damage to or failure of a single clip represents a financial burden out of all proportion to the fault. Moreover, hooks and needles wear-in together and it is best to retain the same hook with a particular needle whenever possible.